The present invention relates to a system for removing labels from containers in general, and in particular for washing plastic bottles and for releasing and separating labels and other contaminants from plastic bottles for further use and recycling.
Commercial recycling of post consumer plastic bottle and like containers typically involves the removal of labels from the bottles before the bottles can be further processed for re-use. Labeled bottles usually arrive at a processing facility in the form of large compacted bales that contain many contaminants, such as caps, cap rings, foil and dirt. The labels, whether made of plastic, paper or other material, are almost always glued to the bottles. The delabeling process typically has two general stages: the first is the loosening and/or releasing of labels from a stream of bottles; and the second is the separation and removal of the labels from the stream of bottles.
While the delabeling process may be done by hand, this is an extremely inefficient and expensive option in a large volume commercial operation. Hence, mechanical delabeling processes have been developed, but the label separation efficiencies remain fairly low. First, there is room for improvement in the release stage to decrease the amount of fluid (usually water) and energy required for label liberation. Second, the most notable problem remains the inefficiencies in separating the released labels from the bottle stream.
Many different processes have been developed, such as those employing high-pressure jets of water or pocketed conveyors for holding and moving individual bottles. While such methods may work with a uniform stream of solid bottles of a specific shape, such as glass bottles, they can not effectively handle a stream of plastic bottles of various shapes and sizes, many of which are crushed or otherwise deformed and damaged.
Another currently employed process which targets plastic bottles typically employs a high rpm (revolutions per minute) drum for aggressively removing labels from the bottles, and some kind of perforated screen for label separation. Such screens sometimes resemble ones used to screen gravel or dirt, namely a long cylindrical shell with perforations thereabout, but designed to have separated labels exit through the perforations and to have the delabeled bottles exit at the far end of the shell. A problem with such perforated shells is that even with short use, the perforations get plugged with labels and plastic bottles, hence requiring either frequent cleaning (which is not practical) or another (secondary) stage of label separation, such as hand sorting of the exiting stream of bottles and labels.
Yet another process employs counter-rotating shakers or shaker tables for label removal, but there is a relatively high loss of bottles into the removed label stream, particularly with those bottles where the labels remain attached and can""t be shaken off. Hence, some of the delabeling and removal must usually be supplemented by hand. Further, water removal from the bottles is generally inadequate with such systems.
What is therefore desired is a novel label removal and separation system with a high efficiency for label separation from plastic bottles of various shapes and sizes. The label release stage should provide for label liberation with the use of steam and a minimum of hot water. Alternately, steam alone should be used to minimize or eliminate the introduction of water into the bottles, and hence to minimize or eliminate the need for subsequent water extraction from the bottles. A drum rotated at low rpm should be employed to agitate the bottles, and to reduce wear and tear on machinery and operating costs. A distinct label separation stage should be provided after the label release stage for effective and efficient separation of labels from the bottles. The separation stage should employ a series of rollers, rather than a perforated drum or shaker, to urge the labels away from the stream of bottles and labels exiting the removal stage. Preferably the series of rollers should allow the labels to be discarded below the rollers and the delabeled bottles to be substantially de-watered and transported over the rollers for further processing.
In a first aspect the invention provides a system for releasing and separating labels from containers comprising a release portion for mixing the containers with an introduced fluid and for providing the containers with a sufficient retention time and agitation to clean the containers and release the labels therefrom; and, a separation portion for receiving the containers and labels from the release portion, the separation portion comprising a plurality of rollers adapted to urge the labels and introduced fluid away from the containers.
In a second aspect the invention provides an apparatus having a releaser and a separator for removing labels from a stream of containers wherein the releaser comprises a rotatable hollow drum member housing a helical screw member for urging the containers through said drum member and for mixing said containers with fluids introduced therein, said drum member being adapted to provide said containers with adequate retention time and agitation to clean said containers of contaminants and release said labels therefrom.
In a third aspect the invention provides an apparatus having a releaser and a separator for removing labels and fluids from a stream of containers wherein the separator comprises a plurality of rollers adapted to urge the labels and fluids away from the containers, the rollers being driven in a counter-rotating manner to the prevailing movement of the containers along the rollers.
In a fourth aspect the invention provides a method for removing labels from containers comprising the following steps:
feeding a plurality of the containers into an upstream end of a releaser;
introducing fluids into the releaser;
maintaining a temperature within the releaser sufficient for cleaning the containers and for urging the release of the labels therefrom;
revolving the releaser to propel the containers and labels toward a downstream end of the releaser;
oscillating the releaser to provide sufficient retention time and agitation for washing the containers and promoting label release;
discharging the containers, labels and fluids from the downstream end of the releaser toward a first end of a separator;
passing the discharged containers and labels onto a plurality of rollers of the separator;
urging the containers to travel by gravity over the rollers by maintaining the separator inclined;
driving the rollers in a counter-rotating manner to the prevailing travel of the containers along the rollers for urging the labels away from the containers; and,
discharging the labels from the separator in a first direction and discharging the containers from the separator in a second direction for further processing.